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Photo glossary of volcano terms

Mud volcano in Norris Geyser Basin, Yellowstone National Park, Wyoming

Photograph by S.R. Brantley in September 1983

Mud volcano in the Norris Geyser Basin, Yellowstone National Park, Wyoming. The mud volcano is about 40 cm tall.

Mud volcano
A mud volcano is a small volcano-shaped cone of mud and clay, usually less than 1-2 m tall. These small mud volcanoes are built by a mixture of hot water and fine sediment (mud and clay) that either (1) pours gently from a vent in the ground like a fluid lava flow; or (2) is ejected into the air like a lava fountain by escaping volcanic gas and boiling water. The fine mud and clay typically originates from solid rock--volcanic gases and heat escaping from magma deep below turn groundwater into a hot acidic mixture that chemically changes the rock into mud- and clay-sized fragments.

 

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U.S. Department of the Interior, U.S. Geological Survey, Menlo Park, California, USA
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Last modification: Monday, 04-Sep-2000 22:44:29 EDT (SRB)